A suture refers to a thread that is used to stitch a portion of a human body damaged by surgery or external injury. Since the beginning of use of sutures, widely employed has been catgut, which is made from intestinal extracts such as intestines, tendons, etc. of sheep, pigs or horses, but the use thereof is gradually decreasing because of incompatibility due to low strength, tissue rejection and fear of animal-derived diseases. Thereafter, alternative materials, such as nylon, silk, and the like, which are synthetic polymers having good properties, have been developed and widely utilized, but are disadvantageous because they have to be removed through additional surgery a predetermined period of time after being applied owing to the non-degradability and non-biocompatibility in the human body, and thus the use thereof is limited.
Accordingly, studies on the development and application of synthetic polymer sutures having ester bonds that are degraded upon prolonged exposure under water-soluble conditions have been continually conducted since the 1970s, and polyglycolic acid (PGA) was used early on, after which a polydioxanone (PDO) polymer or the like came to be widely used as a suture material.
Suture includes absorbable suture that is naturally absorbed in the body to thus obviate removal thereof after wound healing, and non-absorbable suture that requires removal after wound healing.
In the case of absorbable suture, degradable polymer materials such as PGA and PDO are mainly used for internal surgery, and in the case of non-absorbable suture, non-degradable polymer materials such as silk and nylon are mainly used for external surgery. Recently, the use of degradable suture that obviates post-treatment for removal after surgery is increasing. However, an absorbable suture having an ester bond composed of a chemical synthetic polymer causes a fear of side effects due to a foreign rejection reaction at the beginning of use, and degraded residue is present for a long period of time in the body even if degraded by body fluids in the body over time, and thus increasing biocompatibility and safety is regarded as more important.
These days, the use of such degradable sutures as beauty-related materials, such as lifting sutures for counteracting wrinkling, rather than for the original use thereof as a tissue repair material for tissue bonding after internal and external surgery, has greatly increased. The price of typical biodegradable suture amounts to 6˜10 million won per kg, but the price of biodegradable suture made of the same material reaches at least 100 million won per kg upon lifting use, and thus the added value thereof is high, and interest in the development and application thereof is increasing.
Hyaluronic acid (HA) is a kind of glycosaminoglycan (GAG), which is an intermediate between chondroitin and heparin, and is a biopolymer widely present in the skin, muscles, cartilage, blood vessels, etc. in the human body. HA is an important ingredient for cell proliferation and activation in the human body, and it is known as a key element of anti-aging because the amount thereof is reduced in the body with aging to thus promote aging. Recently, the effect of HA on skin regeneration and anti-wrinkling through moisturizing and maintenance of elasticity has been confirmed, and thus the demand for beauty-related cosmetic products, foods and medical filler products is drastically increasing.
Generally, for ideal wound healing of a wound site, after intervention for the prevention of external contamination, cell proliferation and regeneration of the wound site, deposition of the substrate, and then closure of the wound quickly occur, and thus the wound is healed without adhesion or scarring. Methods of promoting such wound healing include, first, injecting a matrix serving as a substrate for wound healing, second, directly administering a growth factor capable of facilitating the expression of skin regenerative cells or therapeutic cells at a high concentration, third, administering an anti-inflammatory substance to suppress inflammation, and fourth, administering an anti-infection antimicrobial substance. Here, when only an in-vivo matrix such as HA is injected as a tissue repair material, the effect as a substrate in the human body may be expected, but in the case of direct administration of the growth factor, the growth factor is expensive, thus imposing price burdens and a difficulty in controlling the activity thereof upon administration. Furthermore, the addition of anti-inflammatory and antimicrobial substances is required for safety.
Thus, addition of the matrix such as HA with chitosan, chitin or lysine having anti-inflammatory and antimicrobial properties and with a compound such as triclosan is regarded as very effective, but a thorough review of the safety and properties thereof is required.
When a PDO suture, which is currently widely useful as a degradable suture using a synthetic polymer, is used as a material for internal surgery or as a material for external surgery such as skin junction in the human body, there is a concern about deterioration of the properties thereof due to low stability for body fluids compared to conventional non-degradable materials, and the use thereof is limited. Also, when it is used for the skin of the face as a suture for internal surgery or lifting, there is a concern about side effects such as a tissue rejection reaction due to an initial in-vivo foreign reaction and problems caused by absorption and discharge due to the degraded residue over the medium and long term after the injection. In particular, upon use as a lifting material for cosmetic surgery for a face, etc., side effects may occur, thus resulting in the deformation of outward appearances, rather than beauty improvement, which is the original goal of treatment. However, most studies for solving such problems have been merely limited to the production of degradable sutures by the addition of antimicrobial and anti-inflammatory ingredients or additives for improving mechanical properties, followed by melt spinning.
In the case of HA, many attempts have been made to manufacture a suture by adding HA to a degradable polymer suture material or to perform coating with HA during post-treatment after manufacture of the suture, in order to exhibit a skin filler function and various effects of improving elasticity and anti-wrinkling in the human body. However, upon the manufacture of a suture by adding a conventional suture material with a small amount of HA and then spinning it, the mechanical properties of the final suture may significantly deteriorate due to the insolubility of HA, and upon coating with HA during post-treatment after the manufacture of the suture, it is difficult to control the thickness of the suture due to high-viscosity HA, and the suture may be damaged by water in the HA aqueous solution used in the coating process, thus causing a concern of drastic deterioration of mechanical properties, and thus, there are no clear results.
Japanese Patent Application Publication No. 2011-31034 discloses a coated suture containing hyaluronic acid and a blend of a polymer derived from a vinyl lactam polymer with a polymer derived from a lactone polymer, but suffers from deteriorated mechanical properties as mentioned above.
Therefore, the present inventors have made efforts to solve the above problems and thus have ascertained that, when a suture is coated with a hyaluronate organic-solvent aqueous solution obtained by dissolving a hyaluronate in purified water and then adding an organic solvent thereto, a high-functional suture, in which the outer appearance and mechanical properties of the suture are maintained and biocompatibility and various physiological activities in the human body may be enhanced, may be manufactured, thus culminating in the present invention.